title: On the mechanisms enabling myocardial edema contrast in bSSFP-based imaging approaches.
abstract: The biophysical mechanisms influencing balanced steady-state free precession (bSSFP) based edema imaging in the setting of acute myocardial infarction are not well understood. To assess the various mechanisms that enable the detection of myocardial edema on bSSFP-based imaging approaches (cine bSSFP and T(2)-prepared bSSFP), experiments were conducted in canine models subjected to ischemia-reperfusion injury. Results showed that in addition to relaxation effects, the alteration in thermal equilibrium (M(0)) (including magnetization transfer) has a significant contribution to the image contrast between edematous and healthy myocardium. The relative signal-intensity ratios between edematous and healthy myocardium were: 1.51 ± 0.18 (cine bSSFP) and 1.58 ± 0.20 (T(2)-prepared bSSFP); the theoretically estimated relative relaxation and M(0) effects were: 1.17 ± 0.09 and 1.30 ± 0.19, respectively (cine bSSFP), and 1.49 ± 0.23 and 1.06 ± 0.07, respectively (T(2)-prepared bSSFP). There were no significant difference between cine bSSFP and T(2)-prep bSSFP relative signal-intensity ratios. However, the relative relaxation effect in cine bSSFP was significantly lower than in T(2)-prep bSSFP (P < 0.05), and the M(0) effect in cine bSSFP was significantly higher than in T(2)-prep bSSFP (P < 0.05). Hence the acquisition strategies that wish to maximize myocardial edema contrast in cine bSSFP imaging should take both relaxation and M(0) effects into account.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, Illinois, USA.
authors.forename: Xiangzhi
authors.initials: X
authors.lastname: Zhou
authors.forename: Veronica
authors.initials: V
authors.lastname: Rundell
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Richard
authors.initials: R
authors.lastname: Tang
authors.forename: Saurabh
authors.initials: S
authors.lastname: Shah
authors.forename: Sven
authors.initials: S
authors.lastname: Zuehlsdorff
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
authors.forename: Rohan
authors.initials: R
authors.lastname: Dharmakumar
mesh_terms: D000465:Algorithms; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004487:Edema / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine; D009206:Myocardium / Q000473:pathology*; D012015:Reference Standards; D015427:Reperfusion Injury; D012815:Signal Processing, Computer-Assisted